长江河口水流输运时间研究  

The study of the transport timescale in the Changjiang Estuary

作　　者：王亚[1] 何青[1] 沈健 

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200062 [2]Virginia Institute of Marine Science,College of William and Mary,Gloucester Point,VA.,23062,USA

出　　处：《海洋学报》2014年第1期48-55,共8页

基　　金：国家自然科学基金项目(41076051;41276080);水利公益专项(201201068);上海市科委重点基金(12231203101);博士研究生学术新人奖(XRZZ2010028)

摘　　要：利用水龄理论的新方法,借助环境水动力学模型定量讨论了多年平均径流条件下长江河口径流和潮汐作用对河口水流输运时间的影响。研究给出了长江河口水流输运时间的时空格局:多年平均流量条件下,水流从徐六泾输出至河口(122.5°E)大约需要24d,南、北槽分流口以上河段水流输运时间主要由径流控制,水流输运时间为8d,向下至拦门沙滩顶水域由径流和潮汐共同控制,水龄为16d,说明最大浑浊带区域的水流输运速度较上下游为慢,从一个侧面阐述了最大浑浊带区域水动力的特征;长江河口水流输运时间存在明显的层化现象,表底层相差最大值可达6d。数值模拟试验结果表明长江河口的潮汐作用是影响河口水流输运时间的关键要素,河口巨大的进潮量增强河口水流交换能力并减小水流输运时间,从而显著影响随水体运动的物质输运格局。水流输运时间研究,不仅可以成功应用于河口水动力环境的量化研究,而且可以为泥沙输运及污染物输运等环境变化研究提供动力的基础。The water age concept is applied to the Changj iang Estuary to quantitatively study the influences of tide and river discharge on the transport timescale under the long-term mean flow discharge condition based on numeri-cal model simulations.The study provides the spatial structure of the mean transport timescale of freshwater in the estuary.The result shows that it takes approximately 24 days for the water to be transported from the Xuliujing to the mouth of the Changjiang Estuary（122. 5°E）.The transport timescale is dominated by the river discharge on the upstream portion of the estuary prior to the bifurcation between the South Channel and the North Channel.The mean transport time is 8 day in this area.From the bifurcation location to the middle portion of the North Passage, both the river runoff and tide affect the transport timescale,and the transport time is about 1 6 days in this area, indicating that the transport rate is slower than both the upstream and the downstream.The stratification impact on transport timescale is evident in the Changjiang Estuary.A 6 day difference of transport timescale between the surface and bottom is observed.The numerical experiment results indicate that the tide is the key forcing affecting the transport timescale in the estuary,which increase exchange rate and decreased the transport time in the Changjiang Estuary.This study illustrates that the water age concept can not only be used to investigate the trans-port of water,but also provide the underlying hydrodynamics for the transport of pollutants and suspended sedi-ment in the Changjiang Estuary.

关 键 词：长江口 潮汐作用 水流输运时间 水龄 数学模型 

分 类 号：P343.5[天文地球—水文科学]